Clonidine is a unique centrally-acting antihypertensive used extensively in clinical medicine. See "Catapres In Hypertension," M. E. Conolly, Ed., Butterworth and Co., London, England, 1970. Due to the high potency exhibited by the drug coupled with individual blood pressure responses shown by patients, it is desirable to monitor the level of clonidine in the biological fluids of patients so that the proper dose regimen may be determined. Thus a sensitive method for the determination of clonidine in body fluids would represent a significant advance in the art.